Thought she was very sick....and popped out an egg!

I have 6 pullets and I get 4 eggs most days for the past 3 weeks. I don't know who is laying them. Today I came home from work and went out to give them yogurt. Nothing unusual happening. Then about a half hour later I went out and one was just standing there, all puffed up with tail feathers pointing down. Not moving, nothing. I got on here and only found one post similiar...that one got better overnight, no known cause. She went to the corner for about 15 minutes, then walked very slowly to the water and drank (I felt a bit better) stood there about 15 more minutes, eyes closing, very still. I felt her crop, not hard. Then about 10 minutes later I see from window she is pecking at the ground. Yeah! Then she is totally normal. I go out to look, there is a tiny egg right where she was standing all that time. Could this just be her first, and it was a little hard coming out???? Will it always be like that? Wow, I was scared!

It sounds like it probably was her first, but... Nah, won't always be that way. Pretty sure she'll be popping them out just like it's nothing much. Maybe a little squawky cackling etc... but not so much.